CRM1 and chromosomal passenger complex component survivin are essential to normal mitosis progress and to preserve keratinocytes from mitotic abnormalities.

OBJECTIVE: Human epidermis provides the body a barrier against environmental assaults. To assume this function, the epidermis needs the renewal of keratinocytes allowed by constant mitosis, which replace the exfoliating corneocytes. Keratinocyte stem cells (KSCs) located in the basal epidermis are mitotically active, self-renewing and govern the epithelial stratification by producing renewed source of keratinocytes. Protein complex such as the chromosomal passenger complex (CPC) allows the correct development of this process. The CPC is composed of four members: INCENP, survivin, borealin and aurora kinase B, and the disruption of the CPC during cell division induces mitotic spindle defects and improper repartition of chromosomes. The aim of our study was to investigate the implication of CRM1 and survivin in the progress of mitosis in skin keratinocytes. METHODS: Cultured human keratinocytes and skin biopsies were used in this study. KSCs-enriched population of keratinocytes was isolated from total keratinocytes by differential attachment to a type IV collagen matrix. Survivin and CRM1 expression levels were assessed by immunofluorescence and immunoblotting. Specific siRNAs for each CPC member and for CRM1 were used to determine the relationship between these proteins. Survivin-specific siRNA was used to induce the apparition of mitotic abnormalities in cultured keratinocytes. RESULTS: We demonstrated the ability of our compound 'IV08.009' to modulate the expression level of survivin and CRM1 in keratinocytes and in skin biopsies. We observed that members of the CPC are interdependent: siRNA-induced inhibition of one component caused a decrease in the expression of all other CPC members. Downregulation of survivin or CRM1 induced mitotic abnormalities in keratinocytes. However, decreased number of mitotic abnormalities was observed in keratinocytes after 'IV08.009' application. CONCLUSION: Basal keratinocytes may divide frequently during skin lifespan, and signs of deterioration could appear such as loss of protein factors required for correct mitosis. Our findings suggest that mitotic abnormalities can be prevented by the modulation of CRM1 and survivin. We demonstrated the ability of compound 'IV08.009' to efficiently protect cultured keratinocytes from mitotic abnormalities.

Evaluation of light-emitting diodes (LED) effect on skin biology (in vitro study).

BACKGROUND: Interest in anti-aging approaches has grown significantly in recent years. The most popular are the non invasive methods to decrease the signs of aging. One such method is LED-based therapy. METHODS: This study investigated the potential of two different wavelengths, 590 nm and 630 nm, combined or not, in the photobiomodulation of proteins involved in the slowdown of the skin aging. RESULTS: These in vitro results on cell viability, cell shape, and mitochondrial function support and build on previous studies suggested that LED treatment is safe. Regarding its biological functions, our data indicated that the combination of two different wavelengths acted in synergy to enhance the impact of each irradiation alone. Combined, the LED wavelengths could improve in vitro the cell shape, the cell proliferation, and the level of major proteins involved in the healing process. CONCLUSION: These benefits may lead to reinforcement of the skin organization and structure. This hypothesis will be checked in future clinical studies.

Evaluation of THP-1 cell line as an in vitro model for long-term safety assessment of new molecules.

OBJECTIVE: Monitoring the chronic and subacute toxicity is essential in the development of new cosmetic ingredients. In response to the present lack of validated alternative methods, we developed an in vitro model for repeated dose cytotoxicity on THP-1 cells. METHODS: Cultured in suspension, cells were treated with chemicals for 14 days with a frequency of three applications per week, and cell viability was determined by MTT assay. We first investigated the long-term effects of chemicals that induce different kinds of cytotoxicity: Paraquat (PQ), 3-Nitropropanoic acid (3-NPA) and sodium dodecyl sulphate (SDS). From acute studies, doses between 1 and 10 µg ml(-1) were chosen to perform our subacute cytotoxicity assay. Comparative genotoxicity evaluations were made with H2 O2 or Paraquat treated TPH-1 cells. Comet assays were performed at 1 h (4°C); after a 24-h recovery period (37°C); and finally, after a long-term period of treatment (14 days, 37°C).Once adapted to plant extracts or highly diluted molecules, some of our cosmetic compounds were tested with this model. RESULTS: As expected, after 14 days of treatment with Paraquat, cell viability rates dramatically decreased for doses as low as 3 µg ml(-1) , whereas 10 µg ml(-1) of 3-NPA and SDS did not induce more than 44% of cell death. Surprisingly, after subacute treatment, comet assay results revealed a dose-dependent increase in tail moments for Paraquat, whereas those of H2 O2 remained low. Moreover, all our compounds tested at 0.5-5 µg ml(-1) were classified as safe, even with a cut-off at 90% of cell viability. CONCLUSION: In conclusion, this assay could be of interest for subacute cytotoxicity and genotoxic assessment of daily and topically applied products and suggests that PQ is a choice worthy positive control.

Impact of AQP3 inducer treatment on cultured human keratinocytes, ex vivo human skin and volunteers.

One of the main functions of the skin is to protect the organism against environmental threats, such as thermal stress. Aquaporin-3 (AQP3) facilitates water and glycerol transport across cell membranes and therefore regulates osmotic balance in different situations of stress. This mechanism seems to be particularly important for the resistance of different organisms to cold stress. Consequently, we were interested in investigating the effect of cold and osmotic stress on AQP3 expression in normal human keratinocytes. We developed a new active ingredient to stimulate aquaporins in skin and demonstrated the partial restoration of AQP3 expression in keratinocytes transfected with AQP3 siRNA. Moreover, we examined the effect of cold stress on cell morphology and the impact of a pre-treatment with the active ingredient. Our results indicated that induction of AQP3 helped maintain a correct organization of the actin cytoskeleton, preserving cell morphology and preventing cells from rounding. Immunofluorescent staining revealed cytoplasmic localization of AQP3 and its translocation to the cell membrane following osmotic stress. Histological ex vivo studies of skin under different conditions, such as cold environment and tape-stripping, indicated that increase in AQP3 expression appears to be involved in skin protection and showed that the pattern of AQP3 expression was more enhanced in the active ingredient-treated samples. In vivo confocal microscopy by Vivascope showed a generally healthier appearance of the skin in the treated areas. These results attest to the potential value of the active ingredient in optimizing environmental stress resistance and protecting the skin from stratum corneum damage.

Microarray profiling of gene expression in human keratinocytes suggests a new protective activity against UV-induced DNA damage for a compound previously known to interact with SCF-KIT signalling pathway.

The stem cell factor (SCF) and its protein-tyrosine kinase receptor KIT are together implicated in the regulation of diverse biological processes and particularly in melanogenesis. Indeed, this signalling pathway controls melanoblast migration from the neural crest during embryogenesis and allows the communication between keratinocytes and melanocytes in the adult. In melanocytes, the binding of SCF to its transmembrane receptor leads to the activation of signalling pathways implicating protein kinases which finally control the expression of pigmentation-related genes. We have developed a biological compound called IV09.007, which we previously described as a modulator of the SCF/KIT signalling pathway with a pro-pigmenting effect. In the present work, we have studied the expression and localization of both SCF and KIT mRNAs and proteins in the skin or skin-derived cell lines. Then, we explored with a microarray approach the ability of IV09.007 to modulate the expression of genes in human keratinocytes and melanocytes in culture. Thereby, we observed the regulation of genes implicated in DNA repair, mainly related to base/nucleotides excision pathways. A modulated transcriptional response was also observed for some genes implicated in the response against oxidative stress, in apoptosis inhibition and in lowering inflammatory immune response. These microarray results predicted a conferred protective effect of IV09.007 and we verified this hypothesis by performing comet assays on UVB-irradiated keratinocytes or melanocytes, to demonstrate the efficacy of IV09.007 on preventing DNA damage.

Maintenance of the ubiquitin-proteasome system activity correlates with visible skin benefits.

Researches on longevity and anti-ageing molecules have clearly evidenced the potential to increase lifespan of the cells. These recent scientific data raise interests and questions on the capacity of the cells to live longer and maintain their fundamental mechanisms of protection, reparation or degradation of abnormal proteins to maintain their capital of healthy and functional cellular activity. In this concern, this study was focused on the ubiquitin-proteasome system as an essential cellular tool to maintain the pool of functionally active proteins allowing renewal of proteins and degradation of damaged proteins. As the proteasome keeps the 'cells health capital', it should be particularly interesting to associate the maintenance of the proteasome activity with increasing longevity. Indeed, although oxidative stress damage increases with ageing leading to collagen and cellular membrane alterations, it also leads to a reduction in the proteasome activity which is critical for the cells. The aim of this study was to better understand the cellular role of the proteasome and to provide new data showing the skin beneficial effects in activating the overall system of ubiquitination and proteasomal degradation. For this purpose, in vitro, ex vivo and in vivo experiments were performed to evaluate the effects of maintaining the ubiquitin-proteasome activity in basal and stress conditions on young versus aged cells. Experiments have included evaluation of a newly developed dimerized tripeptide targeting specifically the ubiquitin-proteasome pathway. Our results have demonstrated that maintenance of this essential mechanism that participates in abnormal protein elimination and protein renewal allows maintaining cellular integrity that correlates with visible skin benefits.

Image analysis to quantify histological and immunofluorescent staining of ex vivo skin and skin cell cultures.

Image processing steps and analysis techniques were developed for the quantification of photomicrographs obtained from light and fluorescence microscopy. The substrates examined were either skin cell cultures, such as normal human keratinocytes (NHK) or fibroblasts, or ex vivo skin sections. Examples of the analyses are provided for the comparison of skincare active ingredient treated samples vs. placebo to demonstrate the utility of the methods to quantify and provide numerical data for a procedure that is typically qualitative in nature and based on observations by a histologist. Quantifiable experiments that are discussed include: Fontana Masson staining for melanin expression; Nile red staining to detect cellular lipid droplets; nuclei staining with diamidino-phenylindole (DAPI); and immunofluorescent staining of protein expression with a primary antibody directed against the protein (antigen) and a secondary antibody tagged with a fluorescent dye (Alexa Fluor 488) against the primary antibody.

Cotton honeydew (Gossypium hirsutum L.) extract offers very interesting properties for hair cosmetics and care products.

Cotton honeydew extract is composed of a unique combination of oligosaccharides, including fructose, glucose, inositol, melezitose, saccharose, trehalose and trehalulose. Studies have shown that these oligosaccharides exhibit a protective effect. Therefore, we were interested in studying the effect of these oligosaccharides on normal and damaged human hair. Both clinical and scanning electron microscopy (SEM) studies were performed. Standardized human hair samples were used to determine the effect of a rinse-off mask with 1% cotton honeydew extract on the ultrastructure of hair. In addition, hair samples were submitted to different aggressions, following various experimental protocols. SEM showed that, without extra aggression, the cuticle scales appeared to lie more smoothly in the hair in cotton honeydew extract-treated samples than in untreated samples. The extract-treated hair samples were also less prone to chipping. In contrast, the control, untreated hair samples retained a dry and damaged appearance and were prone to chipping and progressive splitting. In a clinical study, 15 volunteers had half of their hair treated with a formula with 1% honeydew extract and the other half was left untreated as a control. Pictures and visual evaluation of the hair showed that the honeydew extract formula left the hair with a smoothness that was far superior to the control side and this result was confirmed by SEM. In addition, mRNA studies on epidermal cells were performed and confirmed the stimulating effect of honeydew extract on keratin synthesis. These results demonstrate that cotton honeydew extract can be of great use in hair care products and cosmetics.

Quercus suber cork extract displays a tensor and smoothing effect on human skin: an in vivo study.

Recently, it has become indispensable for anti-aging active ingredients to provide a visible and immediate smoothing antiwrinkle effect. In Quercus suber, suberin is the most important structural component of cork cell walls. Studies have shown that suberin is made up mostly of hydroxycarboxylic acids and that it is endowed with many special mechanical and chemical properties that evoke a possible smoothing effect on the surface of the skin. Therefore, we were interested in investigating the effect of this cork extract on the skin's surface in a double-blind clinical study. The study was conducted in 15 healthy volunteers, aged 22 to 52 years. The volunteers applied a gel formula with 3% of cork extract, or placebo gel, on each forearm. Skin surface roughness was evaluated visually by pictures and by silicone replicas 1 and 2 h after application, followed by statistical analysis using the matched-pairs McNemar statistical test. McNemar analysis of the pictures revealed that application of cork extract on the skin resulted in a highly significant reduction of roughness 1 h after application. This effect was observed in 73.3% of volunteers. Two hours after cork extract application, a highly significant improvement of skin roughness was found in 78.6% of volunteers. Moreover, silicone replica treatment confirmed significant improvement in average of roughness at 2 h. These results demonstrate that cork extract provides a remarkable and highly significant tensor and smoothing effect on the skin, which could be of great use in anti-aging skin care products.

Stimulating effect of collagen-like peptide on the extracellular matrix of human skin: histological studies.

Recent studies of our newly developed synthetic collagen-like hexapeptide have shown that it enhances cultured cell adhesion and differentiation and improves the morphology of ex vivo skin. Consequently, we were interested in further investigating the effects of the collagen-like peptide on the skin. We performed different immunostaining studies on ex vivo human skin samples treated with the collagen-like peptide at 1% in time course studies. Our research also included comparative studies with vitamin C (often used as a positive control for enhancing collagen synthesis). The results showed that application of the collagen-like peptide to the skin enhanced synthesis of many extracellular matrix (ECM) molecules and that this effect was observed very early in some ECM molecules such as laminin 5, collagen 111, and collagen IV The expression of the other molecules was increased after different times of application of the collagen-like peptide. Interestingly, comparative studies with vitamin C showed that the synthesis response of some ECM molecules such as laminin 5, collagen 111 and collagen IV was more rapid after the administration of the collagen-like peptide than through vitamin C administration. Our results also revealed that after a longer treatment period, both active ingredients stimulated ECM molecule synthesis to a similar degree, with the exception of some molecules that remained superiorafterpeptide administration, such as collagen IV and beta 1 integrin. These histological studies demonstrate the remarkable and rapid effect of the collagen-like peptide on stimulating ECM molecule synthesis and suggest wide application for the peptide in antiaging and photoaging skin care products.

Collagen-like peptide exhibits a remarkable antiwrinkle effect on the skin when topically applied: in vivo study.

In this double-blind clinical study, we evaluated the effect of our newly developed synthetic collagen-like hexapeptide on wrinkles. Twenty healthy women volunteers, aged 40 to 62 years old, participated in the study Volunteers applied either a gel formula containing 3% of the collagen-like peptide and 1% of a booster molecule that stimulates general cell metabolism with no specific effect on wrinkles, or a placebo gel, on the eye zone area twice a day for 4 weeks. Control visits were performed at the beginning and the end of the study. Skin wrinkles were evaluated clinically and by silicon replica analysis followed by statistical treatment using the matched-pairs Student's t-test. The results showed that application of the collagen-like peptide on the skin significantly reduced the total surface of wrinkles and this effect was observed in 75% of the replicas. Similarly, the decrease in number and average depth of wrinkles was also significant and was observed in 65% and 75% of the replicas, respectively. The effect of the collagen-like peptide on reducing the total and average length of wrinkles was also remarkable. This effect was statistically highly significant (p < 0.003) and was observed in 75% to 80% of the replicas. Moreover these results were supported by volunteer questionnaires and clinical observation. The results demonstrate that the collagen-like peptide acts deeply and intensely on wrinkles; these properties are of great interest in the field of antiaging skin care research.

The HET-CAM test combined with histological studies for better evaluation of active ingredient innocuity.

In the search for alternative methods to animal testing, the Hen's egg test on chorioallantoic membrane (HET-CAM) plays a central role in evaluating the innocuity of active ingredients. Therefore, in the following studies we combined the HET-CAM test with histological evaluation in order to increase the sensitivity of evaluation. Twenty active ingredients from four different categories of origin (vegetal, marine, biotechnological and chemical synthetic) were subjected to innocuity evaluation at two different concentrations (pure and 10%). We performed the HET-CAM test and histological evaluation after trypan blue and hematoxylin-eosin staining of the chorioallantoic membrane to microscopically evaluate its state of damage after application of each active ingredient. These studies showed that when the active ingredient was diluted (10%), no discrepancy was seen between the classical HET-CAM evaluation and the histological reading of the chorioallantoic membrane. The histological findings corresponded with the visual observation of the CAM. When the active ingredients were tested at pure concentration, 7 out of 20 tested products demonstrated discrepancy between the two tests. In six cases, the histological examination revealed signs of irritation, such as hyperemia, while visual HET-CAM evaluation was negative. In another case, the histological examination revealed a slight hemorrhage whereas the HET-CAM reading showed only hyperemia. Moreover, the results of trypan blue staining corroborated the histological evaluation of the CAM. These results strongly suggest that the combination of histological and visual HET-CAM tests is of interest for a more sensitive evaluation of the innocuity of cosmetic active ingredients. This additional sensitivity may help to prevent some cases of in vivo intolerance reactions.

Date palm kernel extract exhibits antiaging properties and significantly reduces skin wrinkles.

Hormones play a central role in skin appearance and are implicated in skin aging. Recently, along with the remarkable increase in interest in natural products, the application of phytohormones in antiaging products has become very important. In this context, we developed date palm kernel extract. Date palm kernel is rich in phytohormones and we investigated the antiaging properties of date palm kernel in this in vivo study on wrinkles. Ten healthy women volunteers, between the ages of 46 and 58 years, applied the cream formula with 5% date palm kernel or placebo on the eye area twice a day for 5 weeks. The evaluation was made both clinically and by silicon replica analysis followed by statistical analysis using the Wilcoxon test. Silicon replica results showed that topical application of date palm kernel reduced the total surface of wrinkles by 27.6% (p = 0.038). Moreover, date palm kernel reduced the depth of wrinkles by 3.52% (p = 0.0231). These results are statistically significant and were clinically confirmed where visual improvement was seen in 60% of the volunteers treated. This in vivo study demonstrates that date palm kernel exhibits a significant antiwrinkle effect and is therefore of interest in antiaging skin care products.